Electric heating unit



C- 1936- v P. H. VANDEN BERG 2,063,642

ELECTRIC HEATING UNIT Filed Sept. 7, 1933 IIIIIA'IIIIII Inventor-z P ter H. Vanden Bag,

Hi Attorney.

Patented Dec. 8, 1936 UNITED STATES PATENT OFFICE 2,063,642 ELECTRIC HEATING Um Peter H. Vanden Berg, Ontario, Calif assignor to Edison General Electric Appliance Company, Incorporated, Chicago, 111., a corporation of New York Application September 1, 1933, Serial No. 688,410

3 Claims. (Oi. con-s1 This invention relates to electric heating units, ber H and is electrically connected at one end, and has for its object the provision of an imits right-hand end, as viewed in the figures, to a proved and inexpensive device oi this character terminal member l2 which is arranged centrally and method or making it. w of the tubular member ll,but which projects from While not limited thereto, this invention has its end, as clearly shown in Fig. 4. The other '5 particular application to electric heating units of end of the resistance element is electrically conthe sheathed wire type wherein a resistance connected with the corresponding end of the tubular doctor is embedded in; a compacted mass of member H by means of a screw member l3 and a powdered insulating material enclosed by a mewasher M. This screw l3, as shown, is 10 tallic sheath, such as described and claimed in the through an aperture l5 provided for it substan- United States patent to C. C. Abbott, No. 1,367,341, tially in the center of the washer. The washer dated February 1, 1921. V it, therefore, is in mechanical and electrical en- One object of this invention is the provision of gagement both with the tube l' and with the an improved terminal arrangement for electric screw member iii to which the resistance element heating units of this type. Ill is directly connected. 15 In accordance with this invention, a resistance The tubular member II is enclosed by an outer heating element is mounted lengthwise within a metallic sheath it of somewhat larger diameter metallic tubular member. This tubular member and is in concentric relation with it. Y in turn is mounted lengthwise within another me- The resistance element I0 is embedded in a tallic sheath of somewhat larger diameter. One compacted mass of powdered heat refractory end of the resistance element is electrically conelectrically insulating material H, such as magnected with a terminal, which is mounted within nesium oxide. The tubular member il is elecand which projects from the tubular member, trically insulated throughout its length from the while its other end is electrically connected with enclosing sheath It by an electrically insulating 5 the tubular member. The tubular member thus layer l8 formed of a similar insulating material. constitutes a terminal for conducting current to In the finished heater, as shown in Fig. 4, the one end of the resistance element. By reason of two ends of the tubular member II project from the foregoing arrangement, external electrical the associated ends of the enclosing casing 16, connections can be made at one end of the heater. and the terminal member l2 projects from the These connections, however, may be made at associated end of the tubular member ll. 30 both ends, if this arrangement is preferred. By reason of the foregoing arrangement, it will The resistance element is electrically insulated be observed that the tubular member ll constithroughout its length from the tubular member tutes a terminal for one end of the resistance elethat surrounds it and this member is electrically ment completely surrounding the element and 5 insulated throughout its length from the outer also the terminal 12 connected to the other end enclosing sheath. of the element. This arrangement possesses the For a more complete understanding of this inadvantage that the external electrical connecvention, reference should be had to the accomtions may be made atthe same end of the heatpanying drawing, in which Fig. 1 is'an elevation ing unit. This, of course, is desirable when the 0 in section of an electric heating unit arranged unit is to be inserted in an opening in the body 40 in accordance with this invention at one stage oi or article to be heated. On the other hand, the its construction; Fig. 2 is a sectional view taken external electrical connections may be made at through the lines 2-2 of Fig. 1; Fig. 3 is an eleboth ends of the heating unit, if this arrangement vation of the heating unit shown in Fig. 1, but at is desired. Thus, for example, one lead may be 5 a more advanced stage in its construction, porconnected with the terminal l2, while the other tions being broken away so as to illustrate cerlead maybe connected with the left-hand end of tain structural details; and Fig. 4- is a finished the resistance element through the screw l3 and heating unit arranged in accordance with this washer ll. invention, parts being broken away so as to illus- In making the finished heating unit shown in 5 trate certain details of construction. Fig. 4, the helical resistance element 10 is con- Referring to the drawing, in one form of this nected with the screw H which will have been invention, a sinuous or helical resistance element previously inserted through its aperture IS in the It is mounted within and centrally of a metallic washer it. It will be understood that the dimtubular member I I. As shown, the resistance eleeter of the helix is slightly less than the diameter ment It extends lengthwise oi the tubular memof the screw l3 at the roots of the thread so that the helix is expanded somewhat when it is ends of the sheath II are then Deened over, as turned on. The resistance conductor contracts shown in Fig. ,so as to securely hold the washers by reason of its resiliency on the threaded pori4 and the head 22. tion of the screw thereby making a good electrical The entire unit is now passed through a swaging 5 connection with the screw. or rolling machine for the purpose of compacting 5 Then the resistance element is threaded the insulating material within the tubular mem- The washer i4 is received in a recess or counter- In case it is necessary to reduce the diameter 10 bore 20 provided for it in the left-hand end of the oi the unit considerably, it may be desirable to sheath I6, as viewed in Fig. 1. As shown, the pass the unit through the swaging machine a washer I4 is provided with a centrally arranged number 01' times so as to reduce the diameter depressed portion 2| of cup shape. This portion gradually. In this event, the unit may be an- 2| has an external diameter substantially equal nealed between the successive swaging operations 15 to the internal diameter of the tubular member to prevent the resistance element and likewise the II. By reason of this arrangement, the cuptube ii and sheath from becoming too hard and shaped portion 2i functions to position the screw brittle. i3 and the left-hand end of the resistance ele- After the unit has been swaged to the desired ment ill centrally of the tubular member H, extent, the unit is trimmed at the right-hand 20 whereas the washer itself functions to position end so as to remove the head of the terminal 22. the left-hand end of the tube i I centrally of the may be accomplished by cutting oil the enclosing casing it. ends of the tubular member H and the sheath I 2 tioned in the sheath i 6, the right hand end 01' will be cut somewhat shorter than the tube H 25 be understood that the diameter 01 the terminal hand end of the sheath be cut away, as shown 30 connection between the terminal and the resistthis element with the tube ll. 1 35 ance element by the contraction of the helix on The electrical heating unit made in accordance the terminal. with this invention has a very compact and The terminal i2, as shown in Figs. 1, 2 and 3, rugged construction and is arranged so that the is provided with a head 22. The head 22 is electrical connections may be made at either received in a recess or counterbore 23 arranged end of the unit. As previously pointed out, these in the right-hand end of the sheath IS. The connections may be made by connecting suitable head 22 is provided with a shoulder 22a arleads to the terminal l2 and to the protruding ranged centrally thereof and which is received in portion or the casing ii at the right hand end;

shoulder has a diameter substantially equal to nections at the same end they may be made at 45 the right-hand oi the resistance element Ill cenlead will be connected with the washer I I at the trally of the tubular member Ii. The head 22 opposite end of the unit. supports the right hand end of the tubular mem- While I have shown a particular mbodiment oi 50 her ll centrally within the sheath l6. my invention, it will be understood, of course, The head 22 is provided with a plurality of that I do not wish to be limited thereto since sector shaped apertures 2|, as shown in Figs. 2 many modifications maybe made and I, therefore, and 3, through which the insulating material i1 contemplate by the appended claims to cover any and i8 is inserted into the tube H and the such madincations as fall within the true spirit 55 sheath i6. and scope of my invention.

The assembly is now ready for loading the in- What I claim as new and desire to secure by sulating material i l and i8 into the sheath. The Letters Patent 01 the United States. is:

this member and the sheath i6 is filled through unit which comprises connectinga resistance elethe openings 24 provided in the head 22 with ment to a metallic member, mounting said re- 60 the powdered insulating material To accomsistance element in a metallic tubular member phsh this, the sheath I 6 is held in an upright so that said metallic member bears against one position in a special vibrating machine (not end of said tubular member, inserting said tubushown) with the end provided with the apertures lar member in a metallic sheath of larger diamuppermost As the sheath is filled with the rather with said metallic member engaging said insulating material through the openings 24 it metallic sheath so as to position said tubular 1s vibrated to shake the insulating material tomember within said sheath, filling said tubular gather and to distribute it uniformly around the member and the space between said member and 7 resistance element and within the space between said metallic sheath with electrically insulating 7 the tube H and the sheath I6. material, the

25 is inserted in the counterbore 23 so as to cover 2. The method 01' making an electric heating the apertures 24 provided in the head 22. Both unit which comprises connecting one end oi'a sin- 75 uous resistance element to a washer, inserting ance element with reference to said tube, insertsaid resistance element into a metallic tube, poin said tube into a metallic sheath having an insitioning said washer against one end of said tube, ternai diameter approximately equal to the diinserting said tube and resistance element and ameter of said washer so that said washer is re- 5 washer assembled with it into a metallic sheath ceived in one end or said sheath to thereby posi- 5 of somewhat largerdiameter than said tube, setion said tube with respect to said sheath, concuring said tubular member in spaced relation nesting to the other end of said resistance com with said sheath, filling said tube and the space ductor a terminal having a head portion or a dibetween said tube and said sheath with a powameter approximately equal to the internal diaml0 dered heat refractory electrically insulating maeter of said sheath and a shoulder having a diaml0 terial, then compacting said insulating material eter substantially equal to the internal diameter by reducing the diameter of said sheath and then of said tube and further having apertures excutting away said sheath so as to separate it tending through said head and shoulder, assemirom said washer which is connected with said bling said terminal with said tube and sheath so 15 resistance element to electrically insulate the that said shoulder is received in said tube and i5 washer from said sheath. said head is received in said sheath to thereby 3. The method of making an electric heating position said resistance element in said tube and. 'unit which comprises connecting a screw member said tube within said sheath, inserting powdered to one end 01 a helical resistance conductor, seheat refractory electrically insulating material 20 curing said screw member to a washer having a through said apertures so as to fill said tube and 20 cup-shaped central portion, inserting said rethe space between said tube and said sheath with sistance element with said washer attached to it said insulating material, and then reducing the into a metallic tube having an internal diameter diameter of said sheath so as to compact said approximatelyequalto the diameter of said cup insulating material to a hard dense mass. as shaped portion so that said cup is titted into one. s

end of said tube to thereby position said resist- PETER H. VANDEN BERG. 

